Can anyone explain while my coin toss in blender mostly falls on its edge
The Rigid Body simulation uses each objects origin as the centre of mass. If you have objects where the origin is not the centre of mass you will get unexpected behaviour such as that which you are experiencing.

For objects that are constructed of a single substance (eg, coins made of a single metal) you can use the Set Origin option in the tool shelf (T) to get Blender to automatically calculate the centre of mass from the mesh by selecting 'Origin to Centre of Mass'. This will move the origin to the centre of mass based on the mesh and the simulation should behave as would be expected.

Note that you can position the 3D cursor and use the 'Origin to 3d Cursor' option to arbitrarily position the origin (centre of mass) as desired.